As deep ultraviolet lithography becomes widely practiced for producing smaller and smaller microcircuits, e.g. 0.20 μm and smaller, anti-reflective coatings have become essential for improved process designs. These materials provide improved resolution and better critical dimension control by minimizing standing waves and reflective interferences from the substrate.
Antireflective coatings applied at the substrate-resist interface are called bottom antireflective coatings. The ones applied at the resist-air interface are called top antireflective coatings.
Organic antireflective coatings typically work by matching refractive index of the film with that of the photoresist. If there is no change in the refractive index at the antireflective coating and resist interface, there will be no reflection. The organic layers may also be designed to absorb light, so that light that penetrates the antireflective coating is absorbed before it reaches the next interface.
Currently, semiconductor manufacturers use both organic and inorganic antireflective coatings. While either of these classes offers some distinct property advantages, the organic materials offer advantageous spin coating characteristics. Since photo resists and low k dielectrics are applied by spin coating, the antireflective coatings are preferably applied by the same methods. The present inventive materials can be applied by the spin coating techniques.